* {
    box-sizing: border-box;
}

:root {
    --success-color: green;
    --error-color: red;
}

body {
    background-color: #f9fafb;
    display: flex;
    align-items: center;
    justify-content: center;
    min-height: 100vh;
    margin: 0;
}

.container {
    background-color: #fff;
    border-radius: 5px;
    box-shadow: 0 0 10px rgba(0, 0, 0, 0.4);
    width: 380px;
}

form h2 {
    text-align: center;
    margin: 0 0 20px;
}

.container form {
    padding: 30px 40px;
}

.form-control {
    margin-bottom: 10px;
    padding-bottom: 20px;
    position: relative;
}

.form-control label {
    display: block;
    margin-bottom: 5px;
    color: #777;
}

.form-control input {
    display: block;
    border-radius: 4px;
    border: 2px solid #f0f0f0;
    width: 100%;
    padding: 10px;
    font-size: 14px;
}

.form-control.success input {
    border-color: var(--success-color);
}

.form-control.error input {
    border-color: var(--error-color);
}

.form-control small {
    color: var(--error-color);
    position: absolute;
    visibility: hidden;
    bottom: 0;
    left: 0;
}

.form-control.error small {
    visibility: visible;
}

form button {
    cursor: pointer;
    background-color: #3498db;
    border: 2px solid #3498db;
    border-radius: 4px;
    color: #fff;
    display: block;
    font-size: 16px;
    padding: 10px;
    margin-top: 20px;
    width: 100%;
}
